Calibration is the testing of an individual measuring instrument or a sample of measuring instruments for compliance with legally defined requirements by a calibration authority. Measuring instruments can only be calibrated if they meet the essential requirements in terms of measurement technology and their properties. These are regulated in the Measurement and Verification Ordinance. If the measuring instrument complies with the requirements during the verification test, an official mark is affixed for a further verification period to indicate that it can be used for commercial or official purposes and for measurements in the public interest.
The national metrology service for the verification of measuring instruments in Germany is formed by the verification authorities of the 16 federal states and the test laboratories recognized by them. The verification authorities verify measuring instruments
- of trade: e.g. scales, petrol pumps at filling stations, tank trucks for mineral oil, fare gauges in cabs,
- occupational safety and environmental protection: e.g. audiometers, exhaust gas measuring instruments, and
- the police: e.g. breath alcohol measuring devices, radar measuring devices.
The state-approved test centers test utility meters, such as electricity meters, gas meters, water meters and heat meters. More than 120 different types of measuring instruments are subject to calibration. The details can be found in the Measurement and Verification Ordinance. For the different types of measuring instruments, there are different legally prescribed calibration validity periods, which are regulated in the Measuring and Calibration Ordinance (see Appendix 7).